Observation of Bridging Chlorine in Vitreous SiO₂

In this work, we have used multiple spectroscopic methods to examine the change in the network structure of amorphous silica with addition of Cl. Unlike analogous F-doped silicas, where the bonding of halogen leads to terminal Si–F groups, NMR and Raman data for Cl-doped v-SiO₂ indicate bridging between silica tetrahedra, preserving rather than reducing network connectivity and contributing to their elastic stiffness and viscosity behaviors.

These bridging Cl atoms make v-SiO₂ stiffer while having the same effect on density behavior per mol % dopant as F in v-SiO₂ and thus may be a desirable attribute in tailoring v-SiO₂ for optical applications.